1. Technical Field
The present invention relates to a member joining method and a member joining structure, and more particularly, to a member joining method and a member joining structure using resistance spot welding.
2. Related Art
In a joining method and a joining structure used in an automotive body welding line, three or less sheets are normally welded in order to ensure stable quality of resistance spot welding (for example, see Japanese Unexamined Patent Application Publication No. 2012-66795). For this reason, when four or more sheets are welded, for example, a predetermined joint portion is cut out to obtain a structure for welding three sheets.
Different metal materials are often welded in a basic member joining structure, and an intermetallic compound is sometimes produced between the different metal materials. Hence, it is difficult to obtain a member joining method and a member joining structure that ensures sufficient strength. For this reason, the member joining structure actually depends on mechanical fastening such as riveting.
However, in conventional joining structures and methods, when a cutout portion is formed by cutting out a predetermined joint portion, if external force is applied by a collision or for other reasons, a trouble such as deformation originating from the cutout portion is likely to occur. For this reason, the sheet thickness and material have to be changed to avoid such trouble.
In riveting, which is a joining method, a special apparatus and rivets, which are consumer goods, are necessary. This causes new problems in the production line and cost.